SH7708 datasheet(257/633 Pages) RENESAS

257 / 633 page

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10.3.4

DRAM Interface

DRAM Connection Method: When the memory type bits (DRAMTP2–DRAMTP0) in BCR1 are

set to 100, area 3 becomes DRAM space; when set to 101, area 2 and area 3 become DRAM

space. The DRAM interface function can then be used to connect the SH7708 Series directly to

DRAM.

16 or 32 bits can be selected as the interface data width for area 3 when bits DRAMTP2 to

DRAMTP0 are set to 100, and 16 bits can be used for both area 2 and area when bits DRAMTP2

to DRAMTP0 are set to 101.

2-CAS 16-bit DRAMs can be connected, since

CAS is used to control byte access.

Signals used for connection when DRAM is connected to area 3 are

RAS, CASHH, CASHL,

CASLH, CASLL, and RD/WR. CASHH and CASHL are not used when the data width is 16 bits.

When DRAM is connected to areas 2 and 3, the signals for area 2 DRAM connection are

RAS2,

CAS2H, CAS2L, and RD/WR, and those for area 3 DRAM connection are RAS, CASLH,

CASLL, and RD/WR.

In addition to normal read and write access modes, high-speed page mode is supported for burst

access. Also, for DRAM connected to area 3, EDO mode, which enables the DRAM access time

to be increased by delaying the data sampling timing by 1/2 clock when reading, is supported in

addition to normal read and write access for burst mode.

SH7708 データシート(PDF) 257 Page - Renesas Technology Corp